|Publication number||US7110902 B2|
|Application number||US 11/012,383|
|Publication date||Sep 19, 2006|
|Filing date||Dec 16, 2004|
|Priority date||Feb 15, 2002|
|Also published as||DE10306306A1, DE10306306B4, US6847902, US20030155627, US20050109126|
|Publication number||012383, 11012383, US 7110902 B2, US 7110902B2, US-B2-7110902, US7110902 B2, US7110902B2|
|Inventors||Shigetoshi Fukaya, Kenji Takeda, Naoki Nakane, Kiyoshi Sugimura|
|Original Assignee||Nippon Soken, Inc., Denso Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (21), Non-Patent Citations (1), Referenced by (8), Classifications (14), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation of U.S. patent application Ser. No. 10/355,019 which is filed on Jan. 31, 2003, now U.S. Pat. No. 6,847,902, which is based on and incorporates herein by reference Japanese Patent Application No. 2002-38879 filed on Feb. 15, 2002.
The present invention relates to an adjustment-circuit embedded semiconductor sensor and a torsion bar type torque sensor system that uses the adjustment-circuit embedded semiconductor sensor.
A conventional torsion bar type torque sensor system uses a permanent magnet as a magnetic flux generator, so that residual magnetic flux density variation due to temperature variation adversely affects on sensitivity of a torque sensor. Deviation in a size, kind, and material characteristic of the permanent magnet results in fluctuation of the sensitivity and an offset value (zero point output) of the torque sensor.
The conventional torsion bar type torque sensor system is therefore equipped with a temperature sensor such as a thermistor around the permanent magnet. According to temperature detected by the temperature sensor, adjustment for the fluctuation is executed in a circuit outside the sensor.
However, the above method, so-called an external adjustment method, involves additional installment of a separated external adjustment circuit for the adjustment or enlargement of a control section of the torque sensor system when the adjustment circuit is added to the control section of the torque sensor system. This results in increasing a size and cost of the torque sensor system. Furthermore, replacement of the sensor part itself due to its breakdown invalidates previous adjustment data in the above adjustment circuit. This therefore poses replacement of the entire torque sensor system including the external adjustment circuit, which eventually increases cost in maintenance. The above problem occurs not only in the torsion bar type torque sensor system but also in a usual sensor system.
It is an object of the present invention to provide an adjustment-circuit embedded semiconductor sensor and a torsion bar type torque sensor system that adopt the adjustment-circuit embedded semiconductor sensor.
To achieve the above and other objects, an output-adjustment embedded semiconductor sensor is provided with a plurality of sections, which are integrated in the sensor. Here, a detecting section detects at least either of a physical amount and a chemical amount as an electric amount. A thermal detecting section detects a temperature. A non-volatile rewritable memory section rewritably stores adjustment data to adjust an error of the detected electric amount. An adjustment computation section for outputting an adjusted signal after offset adjustment of the detected electric amount, sensitivity adjustment and temperature adjustment, based on the detected temperature and stored adjustment data.
Namely, the semiconductor sensor is formed of a monolithic one-chip IC including the above sections, so that it internally executes the offset adjustment, sensitivity adjustment and temperature adjustment. Breakdown of the sensor therefore involves only replacement of the sensor itself without any replacement nor additional adjustment of the external circuit, which results in simplifying maintenance of the sensor system.
It is preferable that the semiconductor sensor is further provided with an operation control section for externally receiving an operation command and subsequent adjustment data. Here, the operation control section writes the subsequent adjustment data in the non-volatile rewritable memory when the operation command is a writing command. This enables writing of the adjustment data to the non-volatile rewritable memory to be easy.
It is furthermore preferable that when the operation command is a writing-prohibiting command, the operation control section prohibits the writing of the subsequent adjustment data in the non-volatile rewritable memory. This prevents noise or other abnormal events from rewriting false adjustment data to the non-volatile rewritable memory.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
A torque sensor system as a first embodiment of the present invention is used for, e.g., electric power steering equipment. Referring to
The input and output shafts 2, 3 are, relatively rotationally and torque-transmittably, combined by a torsion bar 4. A ring magnet 5 is fixed by fitting it together with the edge of the input shaft 2, while a magnetic yoke 6 is fixed to the edge of the output shaft 3.
The circumferential area of the ring magnet 5 is magnetized in alternate poles at a predetermined circumferential pitch. The magnetic yoke 6 has two magnetic yoke halves 6A, 6B that are fixed coaxially with the output shaft 3 at a predetermined spacing. The magnetic yoke halves 6A, 6B, made of a soft magnetic member, are roughly L-shaped and roughly U-shaped, respectively, in an axial section as shown in
A magnetometric sensor IC 7 is fixed in a stationary state within the axial spacing between the magnetic yoke halves 6A, 6B, for detecting the magnetic field variation in the spacing. Pins 8 are for fixing the torsion bar 4.
In the above structure, application of torque to the input shaft 2 leads to torsion in the torsion bar 4, so that the torque is transmitted to the output shaft 3. Occurrence of relative rotational position difference (i.e., relatively rotated angle) between the ring magnet 5 and the magnetic yoke 6 causes variation in the magnetic flux density between the cylinder hollows of the magnetic yoke 6. This variation of the magnetic flux density is externally outputted.
The magnetometric sensor (M sensor) IC 7 will be explained below, referring to
The logic section 7L detects voltage level applied to the voltage source terminal 7A to determine whether the voltage level corresponds to usual measurement operation or writing operation in the non-volatile memory 7N. When the writing operation is determined, the logic section 7L digitalizes voltage variation of the voltage source terminal 7A to obtain digital signals. The digital signals are written in the non-volatile memory 7N through the lock section 7M. The logic section 7L has a comparator for determining the power voltage level. When the usual measurement operation is determined, the lock section 7M commands prohibition of the writing in the non-volatile memory 7N, based on a command from the logic section 7M.
The computation section 7I, the logic section 7L, and the lock section 7M are formed from well-known generalized circuitry. They are also obviously realized from usual hardware logic circuitry or microcomputer software, so that detail explanation about the circuitry is not described hereunder.
(Usual Detecting Operation)
A usual operation voltage (e.g., 5V) is applied to the voltage source terminal 7A, so that each circuit of the magnetometric sensor IC 7 is supplied with necessary power (electric voltage, electric current).
The oscillator 7F provides each circuit with pulse signals of a constant cycle as the reference clock. An analog voltage value of the magnetic flux density information outputted from the magnetometric sensor 7G is converted by the A/D converter section 7H to digital values to be transmitted to the computation section 7I. A voltage value of temperature information outputted from the thermal detector 7E is transmitted to the magnetometric sensor 7G and the computation section 7I. A measurement signal, indicating that a usual measurement should be executed at present, outputted from the logic section 7L is transmitted to the computation section 7I. The computation section 7I, based on the above information and parameters stored in the non-volatile memory 7N, adjusts the magnetic flux density information detected by the magnetometric sensor 7G to digital information to transmit to the D/A converter section 7J. The digital information is converted by the D/A converter section 7J to analog voltage to externally transmit via the buffer 7K.
An unusual voltage (e.g., 6V and more) other than the usual operation voltage is applied to the voltage source terminal 7A longer than a predetermined period, so that the logic section 7L detects the unusual voltage to determine that a program mode is commanded. The logic section 7L then reads out binarized voltage variation patterns (e.g., high-8V, low-6V) to determine an external command. The external command includes a rewriting command for rewriting the data stored in the non-volatile memory 7N, a data-reading command for commanding the computation section 7I to externally output the data stored in the non-volatile memory 7N via the buffer 7K, and a lock command for retaining the data stored in the non-volatile memory 7N. When the logic section 7L determines the lock command, it commands the lock section 7M to prohibit rewriting of the non-volatile memory 7N. The installment of the lock section 7M prevents wrong rewriting in the non-volatile memory 7N even when voltage variation due to an external disturbance is wrongly determined to be the rewriting command.
A conventional torque sensor system is controlled with a detecting signal of a torque sensor. The conventional torque sensor system is composed of the torque sensor, a torque sensor unit as a mechanical part, and an electronic control unit (ECU) that computes, with the output signal from the torque sensor unit, a control signal to output. Adjustment of a torque sensor characteristic is executed in the ECU by adjusting, before shipment of the system, an adjustment circuit attached to the ECU or by storing adjustment information in a non-volatile memory of the ECU. Breakdown of the above torque sensor unit involves entire replacement of the torque sensor system on site or additional adjustment in the ECU after the partial replacement. Breakdown of the ECU also involves the same procedures similar to that in the breakdown of the torque sensor unit. A lot of recovery work is therefore imposed to the above breakdown.
In the embodiment, the magnetometric sensor, constituting the torque sensor, has the integrated non-volatile memory and various processing circuits, so that offset adjustment, sensitivity adjustment, and temperature characteristic adjustment are executed within the torque sensor. When the torque sensor is broken, the recovery work involves only replacement of the broken torque sensor without adjustment in the ECU. This results in credibly decreasing time and cost of the recovery work. When the ECU is broken, only replacement of the ECU is involved without any additional adjustment in the replaced ECU. Decrease of components in the torque sensor leads to high reliability. Adjustment information can be modified and stored according to other system specifications, so that flexibility to various usages is enhanced.
In this embodiment, adoption of the serial output can prevent several problems resulting from the analog voltage output such as an error from voltage reduction due to wiring resistance, and adverse effect from electromagnetic noise. Additionally, in an ECU that receives the digital signal outputted from the serial output section 70, adverse effect from high frequency noise is decreased through a low-pass filter without decreasing accuracy of the digital signals.
Under the above structure, the magnetic flux enter one of the magnetism-collecting rings 9A, 9B from adjoining one of the annular ring plates of the yokes 6A, 6B. It then proceeds to the other of the manetism-collecting ring 9A, 9B through the mutual plates 9C, 9D. It further proceeds to the other of the annular ring plates of the yokes 6A, 6B. Almost all the magnetic flux is therefore converged between the plates 9C, 9D, passing through a magnetometric sensor IC 7 that is disposed between the plates 9C, 9D. This structure enhances sensitivity of the torque sensor and reduces errors from axial displacement, in comparison with that of the first embodiment shown in
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4784002||Jun 15, 1987||Nov 15, 1988||Atsugi Motor Parts Company, Limited||Torque sensor|
|US4984474||Sep 27, 1989||Jan 15, 1991||Copal Company Limited||Torque sensor|
|US5062062 *||Dec 29, 1989||Oct 29, 1991||Kabushiki Kaisha Toyota Chuo Kenkyusho||Torque detecting apparatus|
|US5241850||Nov 1, 1991||Sep 7, 1993||Texas Instruments Incorporated||Sensor with programmable temperature compensation|
|US5412998 *||Sep 15, 1993||May 9, 1995||Kubota Corporation||Torque measuring system|
|US5577195 *||Sep 3, 1993||Nov 19, 1996||Mitsubishi Denki Kabushiki Kaisha||Semiconductor data storage device with means for protecting data upon external power supply connection and disconnection|
|US5640085||Feb 15, 1996||Jun 17, 1997||Landis & Gyr Technology Innovation Ag||Temperature compensation circuit|
|US5912849 *||Aug 28, 1998||Jun 15, 1999||Hitachi, Ltd.||Write Protection for a non-volatile memory|
|US6176138||Jul 15, 1998||Jan 23, 2001||Saba Instruments, Inc.||Electronic pressure sensor|
|US6283628 *||Sep 11, 1998||Sep 4, 2001||Airpax Corporation, Llc||Intelligent input/output temperature sensor and calibration method therefor|
|US6542848||Jul 31, 2000||Apr 1, 2003||Chart Inc.||Differential pressure gauge for cryogenic fluids|
|US6798184||Jun 27, 2001||Sep 28, 2004||Yamatake Corporation||Integrated sensor device and measuring system using the same|
|US6847902 *||Jan 31, 2003||Jan 25, 2005||Nippon Soken, Inc.||Adjustment-circuit embedded semiconductor sensor and torsion bar type torque sensor system|
|JP2001116643A||Title not available|
|JPH0629290U||Title not available|
|JPH0868606A||Title not available|
|JPH1183420A||Title not available|
|JPH05108989A||Title not available|
|JPH06281513A||Title not available|
|JPS6371800U||Title not available|
|WO2002071019A1||Feb 27, 2002||Sep 12, 2002||Moving Magnet Tech||Position sensor, designed in particular for detecting a steering column torsion|
|1||First Office Action issued from Japanese Patent Office issued on Nov. 18, 2005 for the corresponding Japanese patent application No. 2002-038879 (a copy and English translation thereof).|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7246531 *||Jul 7, 2005||Jul 24, 2007||Denso Corporation||Torque sensor for detecting a shaft torque|
|US7412906 *||Jun 29, 2006||Aug 19, 2008||Globe Motors, Inc.||Steering system torque sensor|
|US7428847 *||Jan 11, 2007||Sep 30, 2008||Jtekt Corporation||Torque detection device|
|US8311760 *||Sep 11, 2008||Nov 13, 2012||Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E.V.||Method for determining, section after section, a parameter-dependent correction value approximation course and sensor arrangement|
|US8800388 *||Dec 17, 2012||Aug 12, 2014||Denso Corporation||Torque sensor apparatus|
|US20050247138 *||Jul 7, 2005||Nov 10, 2005||Denso Corporation||Torque sensor for detecting a shaft torque|
|US20100217556 *||Sep 11, 2008||Aug 26, 2010||Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung E. V.||Method for determining, section after section, a parameter-dependent correction value approximation course and sensor arrangement|
|US20130152702 *||Dec 17, 2012||Jun 20, 2013||Nippon Soken, Inc.||Torque sensor apparatus|
|U.S. Classification||702/99, 702/43|
|International Classification||H01L27/22, H01L43/06, B62D6/10, G01L5/22, G01L3/10, G01K15/00|
|Cooperative Classification||G01L3/104, G01L5/221, B62D6/10|
|European Classification||G01L5/22B, G01L3/10A, B62D6/10|
|Mar 3, 2010||FPAY||Fee payment|
Year of fee payment: 4
|Mar 13, 2014||FPAY||Fee payment|
Year of fee payment: 8